Mechanism for preliminary anchoring of a wire rope bolt

ABSTRACT

The invention relates to a method and mechanism for preliminary anchoring of a wire rope bolt in a bore by means of friction. The object is to eliminate the need to use wooden wedges or to bend the strands of the rope backwards, procedures which are time-consuming. In accordance with the invention, a permanent deformation is produced in the wire rope bolt in such a way that friction force is produced when parts of the bolt press against the wall of the bore. The mechanism may comprise, fitted at a point prior to feeding rolls, a bending roll, which bends the wire rope before it is fed into the bore. The circumference of the feeding roll can be V-shaped, in which case it causes the bent wire rope to rotate and to become helical.

This is a division of application Ser. No. 515,592 filed July 21, 1983,now U.S. Pat. No. 4,617,715.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The object of the invention is a method for preliminary anchoring of awire rope bolt by means of friction in holes drilled in the ceiling orwalls of an excavation. The invention also relates to a mechanism forcarrying out the preliminary anchoring.

2. Description of the Prior Art

A wire rope bolt is anchored in a hole by means of, for example, cementplaster or various chemical mixes. For the duration of the drying of theplaster and mixes and wire rope must be anchored. Previously thepreliminary anchoring has been carried out by using wooden wedges, orthe ends of the strands of the wire rope have been bent backwards, inwhich case the wire rope can be pushed into the hole, but its fallingout is prevented. The disadvantage of these anchoring methods is theirtime-consuming procedure, since the anchoring must be done manually.

SUMMARY OF THE INVENTION

The object of this invention is to carry out the preliminary anchoringof a bolt mechanically in connection with bolting and thereby to speedup the anchoring substantially. In order to achieve this, the inventionprovides a method of the character described above, which comprisesproviding the friction force by producing in the wire rope bolt apermanent deformation in such a way that the bolt in part pressesagainst the wall of the bore. In accordance with the invention, a wirerope is thus anchored preliminarily by producing friction between thebolt and the bore by means of a mechanism which bends the bolt while thebolt is being fed into the bore. The mechanism comprises members forproducing a permanent deformation of the bolt.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below in greater detail with the aid of theaccompanying drawings, in which

FIG. 1 depicts a side view of one embodiment of the mechanism accordingto the invention,

FIG. 2 depicts a top view of the same embodiment, and

FIG. 3 depicts a section of a bore in which a wire rope bolt has beenanchored preliminarily in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The mechanism for feeding and preliminary anchoring of a wire rope boltin general includes a base movable by a power engine of its own. In theaccompanying figures, however, such a base is not depicted, and themechanism shown in the figures comprises only the actual feeding andpreliminary anchoring mechanism.

In FIG. 1, a wire rope feeding roll 2 is attached with bearings to thebase plate 1. Facing the feeding roller above there is a pressing roll3, the shaft of which is attached with bearings at one end, and at theother end of the shaft there is a compressed air cylinder 4 or a similardevice, by means of which the required compressive force is producedbetween the feeding roll and the pressing roll. The wire rope 5 is fedfrom between the feeding roll 2 and the pressing roll 3 into a guidetube 6 and further into a bore. The wire rope 5 is fed, for example frombelow, from point 7 onto a bending roll 8, which is at a different levelvertically than the feeding roll 2. The bending roll 8 is attached bymeans of bearing boxes 9, which can be moved in the feeding direction bymeans of a hydraulic cylinder 10, and thereby the force of the bendingcan be affected.

In FIG. 2 the same mechanism is depicted as seen from the top; thebearing of the shaft of the feeding roll 2 is indicated by numeral 11.

The wire rope bolt 5 is placed between the feeding roll 2 and thepressing roll 3 which is pressed against it by the compressed aircylinder, the feeding roll is caused to rotate by means of the hydraulicengine, and the wire rope is fed into a hole in a rock excavation. Theprofile of the feeding roll, preferably a V-groove, and acoarse-stranded, helical, prestressed steel wire rope bolt 5 tend tocause the wire rope bolt to rotate during the feeding. The bending roll8 is set by means of the hydraulic cylinder 10 in such a way that itcauses the wire rope bolt to bend during the feeding of the bolt. Duringthe feeding the bending causes the bolt to arch, and the simultaneousrotation caused by the shape of the feeding roll causes the wire ropebolt to take a helical shape.

When entering the bore 12, the wire rope bolt 5 becomes tensionedagainst the wall of the bore (FIG. 3) and is kept in the bore byfriction. The arching, and thereby also the spring force of the bolt inthe bore, can be changed by adjusting the position of the bending roll8. A sufficient holding force is obtained even if the whole wire ropebolt is not bent. The required holding force is obtained when thetrailing end of the bolt, preferably 1/5, is bent.

The power engine used for rotating the feeding roll 2 can be, instead ofa hydraulic engine, a compressed-air or electric motor, for example. Thefeeding force can be increased by increasing the number and thecompressive force of the feeding rolls and the pressing rolls. Forexample, screw motors or electric shaft and linear motors are alsousable for adjusting the position of the bending roll.

By means of the method and mechanism described above, a wire rope boltcan be fed into a bore and preliminarily anchored in it. After thepreliminary anchoring, the bolt can be grouted in the bore, and the boltremains firmly in the bore already during the anchoring.

What is claimed is;
 1. A mechanism for preliminary anchoring of a pluralstrand wire rope bolt in a workpiece bore by means of friction,comprising bending members for producing in a continuous operation aspermanent arched deformation in the wire rope bolt, wherein said bendingmembers comprise a bending roll, which is fitted to bend the wire ropebolt, and feeding and pressing rolls, which are fitted to progressivelyproduce a rotary motion and develop a helical shape in the wire ropewhile they feed the wire rope into a guide tube and into the bore.
 2. Amechanism according to claim 1, wherein the position of the bending rollin relation to the feeding roll is adjustable in the longitudinaldirection.
 3. A mechanism according to claim 2, wherein the position ofthe bending roll is adjustable hydraulically or by means of an electricmotor.
 4. A mechanism according to claim 1, wherein the feeding roll isprofiled, preferably with a V-groove-shape, the purpose being to producethe rotary motion of the wire rope bolt.